Micromort
A micromort is a unit of risk defined as a one-in-a-million chance of death. Micromorts can be used to measure the riskiness of various day-to-day activities. A microprobability is a one-in-a million chance of some event; thus, a micromort is the microprobability of death. The micromort concept was introduced by Ronald A. Howard who pioneered the modern practice of decision analysis.
Micromorts for future activities can only be rough assessments, as specific circumstances will always have an impact. However, past historical rates of events can be used to provide a rough estimate.
Sample values
Travel
Activities that increase the death risk by roughly one micromort, and their associated cause of death:- Travelling 6 miles by motorcycle
- Travelling 17 miles by walking
- Travelling 10 miles or 20 miles by bicycle
- Travelling 250 miles by car
- Travelling 1,000 miles by jet airplane
- Travelling 6,000 miles by train
Other
Increase in death risk for other activities on a per-event basis:- Hang gliding – 8 micromorts per flight
- Ecstasy – 0.5 micromorts per tablet, rising to 13 if using other drugs
- Giving birth – 120 micromorts
- Giving birth – 170 micromorts
- AstraZeneca vaccination against COVID-19 – 2.9 micromorts
- COVID-19 infection at age 10, in December 2020 – 20 micromorts
- COVID-19 infection at age 25, in December 2020 – 100 micromorts
- COVID-19 infection at age 55, in December 2020 – 4,000 micromorts
- COVID-19 infection at age 65, in December 2020 – 14,000 micromorts
- COVID-19 infection at age 75, in December 2020 – 46,000 micromorts
- COVID-19 infection at age 85, in December 2020 – 150,000 micromorts
Value of a micromort
Willingness to pay
An application of micromorts is measuring the value that humans place on risk. For example, a person can consider the amount of money they would be willing to pay to avoid a one-in-a-million chance of death. When offered this situation, people claim a high number. However, when looking at their day-to-day actions, a typical value for a micromort is around $50. This is not to say the $50 valuation should be taken to mean that a human life is valued at $50,000,000. Rather, people are less inclined to spend money after a certain point to increase their safety. This means that analyzing risk using the micromort is more useful when using small risks, not necessarily large ones.Value of a statistical life
Government agencies use a nominal Value of a Statistical Life – or Value for Preventing a Fatality – to evaluate the cost-effectiveness of expenditure on safeguards. For example, in the UK, the VSL is £1 million GBP in 1997 value. Since road improvements have the effect of lowering the risk of large numbers of people by a small amount, the UK Department for Transport essentially prices a reduction of 1 micromort at £1.60. The US Department of Transportation uses a VSL of US$6.2 million, pricing a micromort at US$6.20.Chronic risks
Micromorts are best used to measure the size of acute risks, i.e. immediate deaths. Risks from lifestyle, exposure to air pollution, and so on are chronic risks, in that they do not kill straight away, but reduce life expectancy. Ron Howard included such risks in his original 1979 work, for example, an additional one micromort from:- Drinking 0.5 liter of wine
- Smoking 1.4 cigarettes
- Spending 1 hour in a coal mine
- Spending 3 hours in a coal mine
- Living 2 days in New York or Boston in 1979
- Living 2 months with a smoker
- Drinking Miami water for 1 year
- Eating 100 charcoal-broiled steaks
- Traveling 6000 miles by jet